Ignoring AI for the moment, the use of computer models of various kinds has become routine in most if not all professions, whether it’s a simple spreadsheet or a sophisticated engineering in model. It should be no surprise then when such models  make an appearance alongside experts in disputes.

Some recent cases though point up the importance of the expertise that underlies any model and that an expert’s choice of inputs and their interpretation of the outputs is critical. Andrews v Kronospan is a case about dust, smells and other nuisance alleged to be caused by a factory. Experts in dust and wood fibre analysis met and agreed a set of parameters to be used in modelling the likely extend and impact of the factory’s activities, but both the Defendant’s experts for different reasons decide sometime later that these parameters were invalid. They came up with different parameters and different results, that favoured their client, although both provided detailed explanations and reasoning for their decision.

As the judge explained, neither expert has “been able to persuade me that their change of approach was not at least partially influenced by their desire to see whether or not their further analysis would benefit their clients’ case more than their existing analysis. I am not for one moment suggesting that they did not fully and properly discharge their duties as independent experts but I do consider that their evidence has to be considered with some caution as a result. Moreover, I am not satisfied on my analysis of the evidence that I can safely prefer their opinions based on their changed approach to those made by their opposite experts who proceeded on the basis of the initial common approach. “

In a completely different field, fingerprint analysis, there was no criticism of the inputs to an automated fingerprint comparison system. The difficulty was that one expert accepted the computer output as unequivocally correct, whereas the other, with the benefit of 30 years working on fingerprints was able to explain why some features of a fingerprint should be ignored because they typically appear when the print is smeared or of poor quality. Ultimately the judge preferred a manual approach illuminated by scientific knowledge and expertise over one that  treated the computer model as an infallible black box.

 

The message to experts is clear, you need to understand not just how to use a computer model, but what the right inputs are and how to interpret the outputs. Otherwise as the saying goes in the IT Industry you will have Garbage In and Garbage Out!

 

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